3d printing is an interesting technology that is evolving and become popular in recent years. This in part due to the efforts of many people as well as those who took initiatives to make the technology open sourced. it has become an accessible technology which is otherwise limited to the hands of a few research scientists and industrialists.
If you look at the prices of these models, most people would note that they are expensive. The reasons are that unlike conventional mass produced plastic or other material parts, each and every model may take hours to print. And there are quite a lot of post processing (by humans). And especially for metals, there are elaborate multi step processes that includes some form of lost wax casting processes which is used in making precious metals jewellery! Hence, these processes even including the design is not conventional mass production, it is a process comparable to making artworks. However, 3d printing has enabled these artworks to be reproducable so that you could buy them, and each one of them is uniquely made just for you. For instance, you can choose the material or color that you prefer for each model/product.
For all my models, they are orignals (I designed them and worked them myself) and i run 3d printing simulations to verify feasibility before making them available on the shop. Should you have any comments, e.g. things that you would like to see, please do not hestitate to leave me a message